Cookie
A "cookie" is a small piece of information (token) sent by a Web server and stored on a user's system (hard drive) so it can later be read back from that system. Using cookies is a convenient technique for having the browser remember some specific information. Cookies may be categorized as "session" or "persistent" cookies. "Session" cookies are temporary cookies that are used to maintain context or "state" between otherwise stateless Web transactions (e.g., to maintain a "shopping basket" of goods selected during a single logical session at a site) and that must be deleted at the end of the web session in which they are created. "Persistent" cookies remain over time and can be used for a variety of purposes, including to track a user's access over time and across Web sites, or to establish user preferences.

Source:
DoD Web Policy - Amended. Web Site Administraton Policies & Procedures of November 25, 1998 With Amendments and Corrections incorporated... (latest corrections from 11 January 2002).